The paper focuses on the new politicisation processes which characterise the
implementation of source control solutions in Europe. Nowadays, technicians have to
justify their choices not only from a technical point of view but also from a socioeconomic
one. This politisation process is first analysed presenting the strategies
implemented by sewage managers in order to legitimise Best Management Practices
(in comparison to traditional methods). In a second time, we focus on the changes in
the social and technical networks involved in the sewage policies. How do the political
frame (the development of planning and participative procedures) structures the
coalitions favouring BMPs. Relying on the interviews of 14 policy-makers from various
European countries in the field of water management (public and private
organisations in charge of planning and project implementation), we assess to what
extent this politicisation process has allowed the construction of local coherent storm
water management policies.